Volumetric and Dimensional Weight Calculator

Dimensional weight is calculated as length × width × height ÷ divisor. The correct divisor, unit conversion, rounding and minimum charge vary by service, so use the carrier's tariff for the final billable weight.

Formula: dimensional weight = packed L × W × H ÷ divisor, in matching units; billable weight is commonly the larger of dimensional and dead weight. A 30 × 20 × 15 cm parcel at divisor 5,000 is 1.8 kg dimensional weight, while the same dimensions in inches require an inch/pound divisor such as 139.

Measure the outside of the sealed package and preserve the carrier tariff used for the divisor. Minimum billable weights, half-kilogram rounding, girth limits and service exclusions are not universal; a smaller box can reduce cost even when product weight does not change.

Start with the package, not the product. Measure the outside of the sealed carton, mailer or satchel after tape, cushioning and labels are applied. Record the three dimensions in the carrier billing order and use the same unit system for every input. In centimetres, a 40 × 30 × 20 cm carton contains 24,000 cubic centimetres. At a divisor of 5,000 its dimensional weight is 4.8 kg; if the scale reads 3.1 kg, the common chargeable-weight rule would make 4.8 kg the starting point. At a divisor of 4,000 the same box becomes 6 kg, which illustrates why a divisor copied from another courier can produce a material error. Rounding to the next half kilogram or kilogram must be applied only after checking the service tariff.

Packaging decisions often create the largest saving. If the example carton is reduced to 36 × 28 × 18 cm, volume falls to 18,144 cubic centimetres and the 5,000-divisor result is 3.63 kg. That is a reduction of 1.17 dimensional kilograms without changing the product. Do not compress fragile goods beyond their protection requirement, and do not assume a soft bag will be billed at its relaxed shape if the carrier measures the bulge. For multi-piece consignments, ask whether the carrier bills each piece separately or totals the shipment. For pallets, tubes and irregular shapes, a girth or longest-side rule can replace the simple rectangular formula. Use a photo and measurement log when disputing a carrier reweigh or remeasure.

Assumptions and limits: this page does not know negotiated divisors, minimum billable weights, remote-area rules, oversized fees, fuel, residential charges or whether the carrier rounds each dimension before multiplying. Inches and pounds require an inch/pound divisor; converting a centimetre divisor by guesswork can be wrong. Air-express, road and postal products commonly use different conventions. A carrier may also apply an oversize rule even when dimensional weight is low. If actual weight is greater than dimensional weight, actual weight usually drives the comparison, but a tariff can have a minimum chargeable weight. Treat the output as a packaging and quote-screening tool, not an invoice prediction.

Update notes and FAQs: store the carrier, service, divisor, measurement date and scale calibration with the result. Recheck after a carton supplier changes board thickness or after a courier publishes a new tariff. FAQ: Should I round dimensions first? Only if the carrier says it rounds each dimension; otherwise calculate from measured values and apply the published rounding to the result. FAQ: Is volumetric weight the same as DIM weight? They are related names for dimensional billing, but terminology and rules vary by region. FAQ: Why does a lighter parcel cost more? Its occupied space limits vehicle or aircraft capacity, so the carrier prices the space rather than only the mass. FAQ: Can this book a shipment? No; confirm the final quote in the carrier account.